Lead with terminal connector assembly

ABSTRACT

A lead includes a lead body extending from a distal end to a proximal end, and at least one conductor disposed within the lead body and extending from the distal end to the proximal end of the lead body. The lead further includes an outer terminal ring, a terminal pin, and an insulative sleeve disposed between the outer terminal ring and the terminal pin, where the insulative sleeve is coupled with the outer terminal ring with a snap-fit connection. A pin latch is disposed on an outer periphery surface of the insulative sleeve, where the pin latch is rotatable about a hinge point.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application is a division of U.S. patent applicationSer. No. 09/472,098, filed on Dec. 23, 1999, which is acontinuation-in-part of U.S. patent application Ser. No. 09/359,580,filed on Jul. 22, 1999, which is a continuation-in-part of U.S. patentapplication Ser. No. 09/121,005, filed on Jul. 22, 1998, now issued asU.S. Pat. No. 6,141,594; U.S. patent application Ser. No. 09/120,824,filed on Jul. 22, 1998, now issued as U.S. Pat. No. 6,212,434; and U.S.patent application Ser. No. 09/184,226, filed on Nov. 2, 1998, nowabandoned, the specifications of which are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

[0002] The present invention relates generally to implantable leads.More particularly, it pertains to leads having an extendable andretractable fixation mechanism.

BACKGROUND OF THE INVENTION

[0003] Electrodes have been used to stimulate contraction of the heartor to reverse certain life threatening arrhythmias, where electricalenergy is applied to the heart via the electrodes to return the heart tonormal rhythm. Electrodes have also been used to sense and deliverpacing pulses to the atrium and ventricle. Cardiac pacing may beperformed by a transvenous method or by electrodes implanted directlyonto the epicardium. For transvenous pacing systems, a lead having anelectrode is positioned in the right ventricle and/or in the rightatrium through a subclavian vein, and the proximal electrode terminalsare attached to a pacemaker which is implanted subcutaneously.

[0004] Some lead designs have “floating” electrodes or electrodes whichare not attached to the endocardial wall of the heart. The floatingelectrodes lay in the blood pool or against the endocardial wall of theheart and the electrode may move slightly within the heart. Since thelocation of floating electrodes is not fixed with respect to theendocardial wall, the electrical performance of these electrodes variesand is generally less than optimal. Both the electrical sensingcapability as well as the pacing delivery capability of such electrodesare suboptimal. The pacing parameters of such a floating electrode arealso suboptimal. In addition, the floating electrodes can requireincreased voltage which unnecessarily drains the battery.

[0005] As an alternative to floating electrodes, leads have beenprovided with passive fixation elements that affix the electrode to theendocardial wall over time. With passive fixation elements, it can bedifficult to determine whether the lead will affix in the location atwhich it is implanted.

[0006] Active fixation elements, such as a helix, have also beenprovided with distal ends of leads which allow a lead to be affixed tothe endocardial wall. The helix is rotated to screw the lead into theendocardial wall. To rotate the helix toward and into the endocardialwall, a stylet is disposed within the lead and rotated. As the stylet isrotated however, the active fixation element may jump out of the end ofthe lead and damage tissue, and/or the helix. In addition, it isdifficult for the implanter to determine how many turns to the stylet isnecessary to advance the helix a certain distance.

[0007] A cardiac pacing system typically includes a pulse generatorwhich supplies the electrical energy to the lead. The pulse generatormay be implanted into a subcutaneous pocket made in the wall of thechest. A lead coupled with the pulse generator is routed subcutaneouslyfrom the pocket to the shoulder or neck where the lead enters a majorvein, such as the subclavian vein, and into the heart. The proximal endof the lead is coupled both electrically and mechanically with the pulsegenerator at A distal end of the lead is placed within the heart, and aproximal end is placed within a pacemaker.

[0008] When leads with multiple conductors are involved, the conductorsare individually, mechanically and electrically coupled with the pulsegenerator at a proximal end of the multiple conductors. The multipleconductors at the proximal end are electrically insulated from eachother to prevent shorts and limit electrical leakage between conductors.Medical adhesive is used to insulate the multiple conductors at theproximal end of the lead. However, the process of using medical adhesiveis timely and costly. In addition, the medical adhesive bondsinconsistently, sometimes resulting in mechanical and electricalseparation between the components.

[0009] The proximal end of the lead includes a terminal connection whichprovides the electrical and mechanical connection between the pacemakerand the proximal end of the lead. When inserted into the pacemaker, thecomponents of the terminal connection undergoes axial stress as theimplanter forces the proximal end of the lead into the pacemaker. Afterinserted, the implanter may pull on the lead to ensure the terminal endis sufficiently seated in the pacemaker, placing additional axial stresson the terminal connection.

[0010] Accordingly, there is a need for a lead with multiple conductorswhich are reliably insulated from one another. What is further needed isa lead having a terminal connection which can accommodate axial stressplaced thereon.

SUMMARY OF THE INVENTION

[0011] An extendable and retractable lead includes a lead body whichextends from a distal end to a proximal end. A conductor is disposedwithin the lead body and extends from the distal end to the proximal endof the lead body. In addition, the lead includes an electrode basecoupled with the conductor proximate to the distal end of the lead body.The electrode base is threadingly coupled with an outer threaded shell.The electrode base includes external threads disposed thereon. The leadalso includes an active fixation element coupled with the electrode baseand the outer threaded shell.

[0012] In one embodiment, the lead includes a movement assembly which isconfigured to extend and retract the active fixation mechanism. Themovement assembly includes a housing having an internally threadedportion and an externally threaded collar which is engaged with theinternally threaded portion. In another embodiment, the movementassembly further includes an internally threaded insert disposed withinthe lead, where the threaded collar is engaged with the threaded insert.

[0013] In yet another embodiment, the outer threaded shell is formed ofpolyetheretherketone. Alternatively, the lead further includes a secondouter shell coupled with the outer threaded shell, where the secondouter shell forms a stop for the electrode base. In one embodiment, thesecond outer shell is formed of polyetheretherketone. The outer threadedshell is coupled with the second outer shell, for example, with epoxy.The epoxy comprises, in one embodiment, a mixture of one part EPOTEK353ND to 1.75 parts EPOTEK 353ND-T. In yet another embodiment, the leadfurther includes a fluoroscopic ring disposed about the fixation helix.

[0014] A lead includes a lead body extending from a distal end to aproximal end. At least one conductor is disposed within the lead bodyand extends from the distal end to the proximal end of the lead body. Anouter terminal ring is coupled with the lead body, and a sleeve iscoupled with the outer terminal ring, and is also coupled with aterminal pin. Optionally, the coupling allows for rotational movementbetween the outer terminal ring and the terminal pin. Alternatively, theterminal pin and/or the outer terminal ring includes anti-rotationfeatures, for instance, V-shaped grooves. The sleeve is coupled with theouter terminal ring and/or the terminal pin with a snap-fit coupling.The snap-fit coupling, in one embodiment, comprises a first and secondset of cantilevered hooks. In another embodiment, the snap-fit includesa ring latch received in a recess. In addition, the sleeve has a pinlatch which folds with interference about a hinge point. Optionally, thesleeve includes a relief groove adjacent to the ring latch and/or thepin latch.

[0015] In another embodiment, a lead is provided which includes a leadbody extending from a distal end to a proximal end. At least oneconductor is disposed within the lead body and extends from the distalend to the proximal end of the lead body. An outer terminal ring iscoupled with the lead body, and a sleeve is coupled with the outerterminal ring, and is also coupled with a terminal pin. The sleeve iscoupled with the terminal pin with a snap-fit connection.

[0016] In yet another embodiment, a lead is provided which includes alead body extending from a distal end to a proximal end. At least oneconductor is disposed within the lead body and extends from the distalend to the proximal end of the lead body. An outer terminal ring iscoupled with the lead body, and a sleeve is coupled with the outerterminal ring, and is also coupled with a terminal pin. The sleeve iscoupled with the outer terminal ring or the terminal pin with apress-fit coupling.

[0017] A lead includes, in another embodiment, a lead body which iscoupled with an outer terminal ring. The outer terminal ring is coupledwith a terminal pin with a snap-fit connection. An insulator is disposedbetween the outer terminal ring and the terminal pin, and in oneembodiment comprises a non-conductive coating. In one embodiment, theouter terminal ring is rotatably coupled with the terminal pin.

[0018] In yet another embodiment, a system includes an electronicssystem which has a pulse generator. The pulse generator is electricallycoupled with a lead which includes a lead body extending from a distalend to a proximal end. At least one conductor is disposed within thelead body and extends from the distal end to the proximal end of thelead body. An outer terminal ring is coupled with the lead body, and asleeve is coupled with the outer terminal ring, and is also coupled witha terminal pin. The coupling allows for rotational movement between theouter terminal ring and the terminal pin. The sleeve is coupled with theouter terminal ring or the terminal pin with a snap-fit coupling. Thesnap-fit coupling, in one embodiment, comprises a first and second setof cantilevered hooks. In another embodiment, the snap-fit couplingcomprises an annular flange received in a recess. In another embodiment,the snap-fit coupling includes a ring latch received in a recess and apin latch which folds about a hinge point. In yet another embodiment,the lead further includes a movement assembly which is configured toextend and retract an active fixation mechanism. The movement assemblyincludes a housing having an internally threaded portion and anexternally threaded collar which is engaged with the internally threadedportion. In another embodiment, the movement assembly further includesan internally threaded insert disposed within the lead, where thethreaded collar is engaged with the threaded insert.

[0019] The lead assembly described above provides several advantages,for example, ease of manufacturability is increased and through puttimes are reduced. The individual components can be snapped together, asopposed to waiting for messy bonding or long cure times. Bonding blocks,used for the bonding process, are eliminated, which are expensive,difficult and costly to clean. A consistent and increased strength ofcoupling is achieved using the snap fit design since bonding is variablebased on the operator. Yet another advantage is that the geometry of thesnap fit connector provides an insulation with a known thickness, whichallows for a repeatable dielectric strength.

[0020] These and other embodiments, aspects, advantages, and features ofthe present invention will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the art byreference to the following description of the invention and referenceddrawings or by practice of the invention. The aspects, advantages, andfeatures of the invention are realized and attained by means of theinstrumentalities, procedures, and combinations particularly pointed outin the appended claims and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a block diagram illustrating a system for deliveringand/or receiving signals to and from the heart constructed in accordancewith one embodiment.

[0022]FIG. 2 is a cross-section illustrating a terminal end of a leadconstructed in accordance with one embodiment.

[0023]FIG. 3 is a cross-section illustrating a distal end of a leadconstructed in accordance with one embodiment.

[0024]FIG. 4 is a cross-section illustrating a distal end of a leadconstructed in accordance with another embodiment.

[0025]FIG. 5 is a cross-section illustrating a distal end of a leadconstructed in accordance with another embodiment.

[0026]FIG. 6 is a perspective view illustrating a portion of a movementassembly end of a lead constructed in accordance with anotherembodiment.

[0027]FIG. 7A is a block diagram of a system with a lead for use with aheart and constructed in accordance with one embodiment.

[0028]FIG. 7B is an elevational view of an example of a lead for use inthe system shown in FIG. 7A.

[0029]FIG. 7C is a cross-sectional view of a lead coupled with a pulsegenerator constructed in accordance with one embodiment.

[0030]FIG. 8 is an exploded perspective view of an assembly constructedin accordance with one embodiment.

[0031]FIG. 9A is an unexploded cross-sectional view of the assemblyshown in FIG. 8 constructed in accordance with one embodiment.

[0032]FIG. 9B is a cross-section view of a portion of a lead constructedin accordance with another embodiment.

[0033]FIG. 10 is an exploded perspective view of an assembly constructedin accordance with another embodiment.

[0034]FIG. 11 is an unexploded cross-sectional view of the assemblyshown in FIG. 10 constructed in accordance with one embodiment.

[0035]FIG. 12 is an exploded perspective view of an assembly constructedin accordance with yet another embodiment.

[0036]FIG. 13 is an unexploded cross-sectional view of the assemblyshown in FIG. 13 constructed in accordance with one embodiment.

[0037]FIG. 14 is an exploded perspective view of an assembly constructedin accordance with one embodiment.

[0038]FIG. 15 is an unexploded cross-sectional view of the assemblyshown in FIG. 14 constructed in accordance with one embodiment.

[0039]FIG. 16 is an exploded cross-sectional view of an assemblyconstructed in accordance with one embodiment.

[0040]FIG. 17 is a cross-sectional view of an assembly constructed inaccordance with one embodiment.

[0041]FIG. 18 is a cross-sectional view of an assembly constructed inaccordance with another embodiment.

[0042]FIG. 19 is an unexploded cross-sectional view of an assemblyconstructed in accordance with one embodiment.

[0043]FIG. 20 is a partially cross-sectional view of a terminalassembly.

[0044]FIG. 21 illustrates a cross-sectional view of a terminal pin of aterminal assembly constructed in accordance with one embodiment.

[0045]FIG. 22A illustrates a cross-sectional view of a terminal pin of aterminal assembly constructed in accordance with one embodiment.

[0046]FIG. 22B illustrates a cross-sectional view of the terminal pin ofFIG. 22A taken along 22B-22B.

[0047]FIG. 23A illustrates a cross-sectional view of a terminal pin of aassembly constructed in accordance with one embodiment.

[0048]FIG. 23B illustrates a cross-sectional view of the terminal pin ofFIG. 23A taken along 23B-23B.

[0049]FIG. 24 illustrates a cross-sectional view of a sleeve of aterminal assembly constructed in accordance with one embodiment.

[0050]FIG. 25 illustrates a cross-sectional view of a sleeve of aterminal assembly constructed in accordance with one embodiment.

[0051]FIG. 26A illustrates a perspective view of an outer terminal ringof a terminal assembly constructed in accordance with one embodiment.

[0052]FIG. 26B illustrates a cross-sectional view of an outer terminalring of a terminal assembly constructed in accordance with oneembodiment.

[0053]FIG. 27 illustrates a cross-sectional view of the outer terminalring of FIGS. 26A and 26B.

DESCRIPTION OF THE EMBODIMENTS

[0054] In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that structuralchanges may be made without departing from the scope of the presentinvention. Therefore, the following detailed description is not to betaken in a limiting sense, and the scope of the present invention isdefined by the appended claims and their equivalents.

[0055] An extendable and retractable lead 110 and lead system 100 areillustrated in FIG. 1. FIG. 1 is a block diagram of a system 100 fordelivering and/or receiving electrical pulses or signals to stimulateand/or sense the heart 102. The system 100 includes a pulse generator105 and a lead 110. The pulse generator 105 includes a source of poweras well as an electronic circuitry portion. The pulse generator 105 is abattery-powered device which generates a series of timed electricaldischarges or pulses. The pulse generator 105 is generally implantedinto a subcutaneous pocket made in the wall of the chest. Alternatively,the pulse generator 105 is placed in a subcutaneous pocket made in theabdomen, or in other locations.

[0056] The lead 110 includes a lead body 113 which extends from aproximal end 112, where it is coupled with the pulse generator 105, asfurther discussed below. The lead 110 extends to a distal end 114, whichis coupled with a portion of a heart 102, when implanted. The distal end114 of the lead 110 includes at least one electrode 116 (FIG. 2) whichelectrically couples the lead 110 with the heart 102. At least oneelectrical conductor 118 (FIG. 2) is disposed within the lead 110 andextends from the proximal end 112 to the distal end 114 of the lead 100.The at least one electrical conductor 118 electrically couples theelectrode 116 with the proximal end 112 of the lead 110. The electricalconductors carry electrical current and pulses between the pulsegenerator 105 and the electrode 116.

[0057]FIGS. 2 and 3 illustrate one embodiment of the distal end 114 ofthe lead 110 in greater detail, where FIG. 2 illustrates the lead 110 ina retracted position and FIG. 3 illustrates the lead 110 in an extendedposition. The electrode 116 comprises a fixation helix 120 which allowsfor the distal end 114 of the lead 110 to be affixed to the heart 102(FIG. 1). The fixation helix 120 is mechanically and electricallycoupled with an electrode base 122. The electrode base 122 ismechanically coupled with the at least one electrical conductor 118,such that as the conductor 118 is rotated, the electrode base 122translates along an axis 113 of the lead 110, as will be furtherdiscussed below. In one embodiment, the electrode base 122 iselectrically coupled with the at least one electrical conductor 118, andthe electrode base 122 is formed of an electrically conductive material,such as metal. Disposed about the electrode base 122 are externalthreads 124, which allow the electrode base 122 to rotate and translatethe fixation helix 120. The electrode base 122 is coupled with an outerthreaded shell 140. In one embodiment, a steroid collar 151is disposedwithin the distal end 114 of the lead 110.

[0058] The threaded shell 140 has internal threads 142 therein. Theinternal threads 142 provide a path for the external threads 124 of theelectrode base 122. As the electrode base 122 is rotated, the externalthreads 124 engage with the internal threads 142 and translate theelectrode base 122 along the axis 113 of the lead 110.

[0059] In one embodiment, the lead 110 includes a stop to prevent thefixation helix 120 from over-extension. The stop comprises, in oneembodiment, a stop 144 on the internal threads 142 which blocks therotation of the external threads 124. Once the external threads 124reach the stop 144, the electrode base 122 can no longer be rotated andtranslated out of the lead 110, which prevents the fixation helix 120from being overextended into tissue of, for example, a heart. In anotherembodiment, the stop comprises a stop 146 formed on an outer shell 145which is disposed adjacent to the electrode collar 130 (discussedbelow).

[0060] The outer threaded shell 140 and/or the outer shell 145, in oneembodiment, is formed of polyetheretherketone (PEEK). In anotherembodiment, the outer threaded shell 140 is formed of PEEK 150G, lowmelt viscosity. For the PEEK 150G, the melt viscosity ranges from about0.12-0.18 KNs/m², and the tensile strength is greater than or equal to90 MPa. The threaded shell 140, in another embodiment, comprises PEEK450G, standard melt viscosity. For the PEEK 450G, the melt viscosityranges from about 0.38-0.50 KNs/m², and the tensile strength is greaterthan or equal to 90 MPa. The PEEK allows for the outer threaded shell140 to be molded, extruded, or machined for tighter tolerances orproviding precision structures. PEEK is a tough rigid thermoplasticmaterial which is biocompatible.

[0061] Proximate to the distal end 114 of the lead 110 is a fluoroscopyring 150, which is disposed about the fixation helix 120. The electrodebase 122 has, in one embodiment, an electrode collar 130 coupledtherewith, such that as the electrode base 122 is translated, theelectrode collar 130 translates along the axis 113. As the fixationhelix 120 is extended out from the lead 110, the electrode collar 130translates toward the fluoroscopy ring 150 until the electrode collar130 abuts a portion the fluoroscopy ring 150, at which point thefixation helix 120 is fully extended. The collar 130 and the ring 150allows the implanter to view, under fluoroscopy, when the fixation helix120 is fully extended.

[0062] As discussed above, the outer shell 145, provides a stop for thetranslation of the electrode collar 130. The outer shell 145 is coupledwith the outer threaded shell 140. Epoxy 190, in one embodiment, isdisposed between the outer threaded shell 140 and the outer shell 145.In one embodiment, the epoxy 190 comprises a blend of two differentepoxies. The two different epoxies are EPOTEK® 353ND and EPOTEK®353ND-Tmade by Epoxy Technology. The two epoxies are mixed in the ratio of 1part EPOTEK® 353ND to 1.75 parts EPOTEK® 353ND-T. The epoxy is cured ata temperature of 150° C. for one hour.

[0063]FIGS. 4 and 5 illustrate another embodiment of a lead 200. Thelead 200 includes a retractable active fixation element 270, whichassists in avoiding injury to the patient during implantation.Alternatively, the active fixation element 270 rotates withouttranslating along the lead 200. The lead 200 further includes a movementassembly 202 disposed at a distal end 214 of the lead 200, where themovement assembly 202 is adapted to transport the active fixationelement 270 in and out of the lead 200 as the active fixation element270 is rotated.

[0064] Referring again to FIG. 4, the movement assembly 202 includesexternal threads 220 associated therewith. In one embodiment, theexternal threads 220 are disposed about a collar 222 of the lead 200.The external threads 220 are adapted to engage with internal threads 226disposed within a housing 224 of the lead 200. The internal threads 226provide a helical path for the external threads 220. The movementassembly 202 is not, however, limited to the components describedherein. For instance, the external threads 220 and the internal threads226 can be provided on alternative components, and still be consideredwithin the scope of the invention. In one embodiment, an insert 230 isprovided for the internal threads 226, as shown in FIG. 5. As shown inFIG. 5, the insert 230 comprises a semi-cylindrical collar 233, wherethe collar 233 is disposed within the lead 200. In another embodiment, atwo-piece insert is provided which includes a first half and a secondhalf. The first half and the second half are coupled together to form acylindrical collar in which there are internal threads. In oneembodiment, the first half and the second half are molded from plasticmaterial. In another embodiment, the first half and the second half aremachined from, for example, hard plastic materials or metal, or thematerials discussed above.

[0065] The insert 230 contains internal threads 226 which are adapted toengage with the external threads 220 of the collar 222. During use, aterminal pin (FIG. 6) is rotated which causes the collar 222 to rotate.As the collar 222 is rotated and the external threads 220 and theinternals threads 226 engage, the active fixation element 270 movesalong the axis 214 of the lead 200. The movement assembly 202 can beused with a wide variety of leads implementing active fixation,including, but not limited to, single pass dual chamber pacing leads,single pass dual chamber pacing/defibrillator leads, single chamberpacing leads, and single chamber pacing/defibrillator leads.

[0066] In another embodiment, a mesh screen 240 is provided at a distalend 214 of the lead 200. The mesh screen 240 allows for better tissuein-growth, as well as enhanced sensing capabilities. The mesh screen 240is disposed proximate to the active fixation element 270. In oneembodiment, as the active fixation element 270 is translated andextended from the lead 200, mesh screen 240 moves with the activefixation element 270. The fixation element 270 engages the heart tissueand draws the mesh screen 240 into contact with the surface of theheart. In yet another embodiment, a steroid 242 is disposed within thedistal end 214 of the lead 200.

[0067]FIG. 6 illustrates one embodiment of the proximal end 112 of alead 300 in greater detail. The lead 300, in one embodiment,incorporates the embodiments discussed for the distal end discussedabove and below. In addition, the proximal end 112 of lead 300 includesa terminal pin 310 which provides the electrical connection between thepulse generator 105 (FIG. 1) and the lead 300. The terminal pin 310 ismechanically coupled with a conductor coil 312. As the terminal pin 310is rotated, the conductor coil 312 rotates, thereby rotating theelectrode base (FIGS. 2 and 3) as discussed above.

[0068] The lead 300 further includes an outer terminal ring 314 which iscoupled with a lead body 316. An insulator sleeve 318 is disposed overat least a portion of the terminal pin 310, and the insulator sleeve 318insulates the terminal pin 310 from the outer terminal ring 314. In oneembodiment, the sleeve 318 is rotatably coupled with the outer terminalring 314.

[0069] The sleeve 318, in another embodiment, is coupled with theterminal pin 310 with a snap-fit connection. Alternatively, the sleeve318 is coupled with the terminal pin 310 and/or the outer terminal ring314 with a snap-fit connection. In one embodiment, the sleeve 318includes at least one projection 320. The at least one projection 320 isengaged with a recess 330 of the terminal pin 310, and prevents theterminal pin 310 from moving axially. The projection 320, in oneembodiment, comprises an annular projection disposed about thecircumference of the sleeve 318, which allows the terminal pin 310 torotate relative to the outer terminal ring 314. The annular projectionengages within an annular recess disposed within the circumference ofthe terminal pin 310. In yet another embodiment, the sleeve 318 furtherincludes at least one recess 322 disposed adjacent to the projection320. The at least one recess 322 receives therein a projection 324 ofthe terminal pin 310. The additional mating male and female componentsprovide increased axial strength to the connection between the lead 300and the pulse generator (FIG. 1). In yet another embodiment, the sleeve318 further includes a stop 360 for the outer terminal ring 314.

[0070] The sleeve 318 is formed of non-conductive material. In oneembodiment, the sleeve 318 is formed of polyetheretherketone (PEEK). Inanother embodiment, the sleeve 318 is formed of PEEK 150G, low meltviscosity. For the PEEK 150G, the melt viscosity ranges from about0.12-0.18 KNs/m², and the tensile strength is greater than or equal to90 MPa. The sleeve 318, in another embodiment, comprises PEEK 450G,standard melt viscosity. For the PEEK 450G, the melt viscosity rangesfrom about 0.38-0.50 KNS/m², and the tensile strength is greater than orequal to 90 MPa. The PEEK allows for the sleeve 318 to be molded,extruded, or machined for tighter tolerances or providing precisionstructures. PEEK is a tough rigid thermoplastic material which isbiocompatible.

[0071] FIGS. 7A-19 illustrate additional embodiments of the lead andlead system. FIG. 7A is a block diagram of a system 1100 for deliveringand/or receiving electrical pulses or signals to stimulate and/or sensethe heart. The system for delivering pulses 1100 includes a pulsegenerator 1105 and a lead 1110. The pulse generator 1105 includes asource of power as well as an electronic circuitry portion. The pulsegenerator 1105 is a battery-powered device which generates a series oftimed electrical discharges or pulses used to initiate depolarization ofexcitable cardiac tissue. The pulse generator 1105 is generallyimplanted into a subcutaneous pocket made in the wall of the chest.Alternatively, the pulse generator 1105 is placed in a subcutaneouspocket made in the abdomen, or in other locations. An enlargement of theconnection between the lead 1110 and the pulse generator 1105 is shownin FIG. 7C, described in more detail below.

[0072] The lead 1110, shown in more detail in FIG. 7B, extends from aproximal end 1112, where it is coupled with the pulse generator 1105,and extends to a distal end 1114, which is coupled with a portion of aheart 1115, in the implanted condition (FIG. 7A). The proximal end 1112of the lead 1110 includes an overmolded portion 1124 which assists insealing the lead 1110 to the pulse generator 1105. The distal end 1114of the lead 1110 includes at least one electrode 1116 which electricallycouples the lead 1110 with the heart 1115. The electrode 1116 is eithera unipolar or bipolar type electrode. In one embodiment, multipleelectrodes are provided. At least one electrical conductor is disposedwithin the lead 1110 and electrically couples the electrode 1116 withthe proximal end 1112 of the lead 1110. The electrical conductors carryelectrical current and pulses between the pulse generator 1105 and theelectrode 1116 located in the distal end 1114 of the lead 1110.

[0073] The body 1111 of the lead 1110, in one embodiment, is cylindricalin shape, and is made of a tubing material formed of a biocompatiblepolymer suitable for implementation within the human body. Although notrequired, the tubing is made from a silicone rubber type polymer. Thelead 1110 travels from the pulse generator 1105 and into a major veinand the distal end 1114 of the lead 1110, in one embodiment, is placedinside the heart 1115. The lead will be either actively or passivelyaffixed to the endocardial wall of a chamber of the heart, depending onthe embodiment.

[0074]FIGS. 8, 9A, and 9B illustrate another embodiment of the leadterminal including a press-fit design. The assembly 1200 includes aterminal pin 1210, a sleeve 1230, and an outer terminal ring 1260, whichare all coupled together such that, after assembly, axial movement ofthe individual components is prevented, as further described below. Theterminal pin 1210 and the outer terminal ring 1260 each provide anelectrical connection in between the lead 1110 and the pulse generator1105, as shown in FIG. 7C, and as further discussed below. The terminalpin 1210 extends from a first end 1212 to a second end 1214. The secondend 1214 is adapted for coupling with the pulse generator 1105, asdiscussed above (FIGS. 7A and 7C). The first end 1212 is adapted to beinserted into other components of the assembly 1200, specifically thesleeve 1230, as will be further described below. The first end 1212 ofthe terminal pin 1210 includes a tapered portion 1216 which facilitatesinsertion of the terminal pin 1210 into the sleeve 1230. In addition,the terminal pin 1210 includes an assembly portion 1220 which isdisposed near the first end 1212.

[0075] The assembly portion 1220, in one embodiment, includes an outersurface 1222 which extends toward an annular ridge 1224. The outersurface 1222 is adapted to be received within the sleeve 1230, asdescribed below. The outer surface 1222 is tapered from the first end1212 towards the annular ridge 1224. The annular ridge 1224 forms anengaging surface which is received and retained by the sleeve, asfurther described below.

[0076] The terminal pin 1210 also includes an internal surface 1218which defines a lumen 1219 therein. The lumen 1219 extends through theterminal pin 1210 from the first end 1212 to the second end 1214 andallows for instruments, such as catheters, stylets, or guidewires, to beinserted through the terminal pin 1210 and through the lead 1110 (FIG.7B). In addition, the internal surface 1218 of the terminal pin 1210provides a coupling surface for a first conductor 1280, as illustratedin FIG. 9B, whereat the first conductor 1280 is electrically coupledwith the terminal pin 1210. The first conductor 1280 provides anelectrical connection between the terminal pin 1210 and an electrode ofthe lead 1110.

[0077] As mentioned above, the assembly 1200 also includes a sleeve1230. In one embodiment, the sleeve 1230 is an insulator between theterminal pin 1210 and the outer terminal ring 1260, where the sleeve1230 electrically insulates the terminal pin 1210 from the outerterminal ring 1260. In addition, the sleeve 1230 provides a mechanicalconnection between the terminal pin 1210 and the outer terminal ring1260. The sleeve 1230 extends from a first end 1234 to a second end1236, where the first end 1234 of the sleeve 1230 couples with the outerterminal ring 1260. The second end 1236 is adapted to couple with theterminal pin 1210. Disposed through the sleeve 1230 is a bore 1232,where the bore 1232 is adapted to receive the terminal pin 1210 therein.The bore 1232 allows for instruments, such as catheters, stylets, orguidewires, to be inserted through the sleeve 1230 and through the lead1110 (FIG. 11B).

[0078] The bore 1232 includes an internal surface 1238 which has acoupling feature 1242 thereon. In one embodiment, the coupling feature1242 includes an annular shoulder 1244. The shoulder 1244 engages theannular ridge 1224 of the terminal pin 1210. The sleeve 1230 alsoincludes an external surface 1240. The external surface 1240, in oneembodiment, is engaged by the outer terminal ring 1260, and is tapered.In one embodiment, the taper extends from the second end 1236 toward thefirst end 1234 of the sleeve 1230.

[0079] The assembly 1200 also includes an outer terminal ring 1260 whichextends from a first end 1262 to a second end 1264. The outer terminalring 1260 includes a coupling portion 1266 which is formed, in oneembodiment, on an internal surface 1268 of the outer terminal ring 1260.In one embodiment, the internal surface 1268 of the outer terminal ring1260 is sized to receive the external surface 1240 of the sleeve 1230therein, such that an interference fit or a press-fit is createdthereby. The interference fit between the sleeve 1230 and the outerterminal ring 1260 retains the sleeve 1230 axially to the outer terminalring 1260.

[0080] To assemble the assembly 1200, the first end 1212 of the terminalpin 1210 is inserted into the second end 1236 of the sleeve 1230. Theterminal pin 1210 is inserted until the annular ridge 1224 engages withthe shoulder 1244 of the sleeve 1230. Once the terminal pin 1210 iscoupled with the sleeve 1230, the sleeve 1230 is then coupled with theouter terminal ring 1260 and axial movement between the sleeve 1230 andthe outer terminal ring 1260 is prevented. The first end 1234 of thesleeve 1230 is inserted into the second end 1264 of the outer terminalring 1260. The sleeve 1230 is inserted into the outer terminal ring 1260until the interference fit is created between the two. Alternatively, inanother embodiment, the sleeve 1230 can be assembled first with theouter terminal ring 1260 prior to insertion of the terminal pin 1210into the sleeve 1230.

[0081] The terminal pin 1210 and the outer terminal ring 1260 are bothformed from conductive material. The sleeve 1230 is formed from anonconductive material, and acts as an insulator between the terminalpin 1210 and the outer terminal ring 1260. The sleeve 1230 can be formedfrom various high-performance engineering plastics, unreinforced andreinforced materials including, but not limited to polysulfone,polyimide, polyamide, polyacetal, polyketone, polyester,polyetheretherketone, polycarbonate, polyolefin, or liquid crystalpolymers. Alternatively, the sleeve 1230 is formed from the materialsdiscussed in the above embodiments. These materials are appropriate forthe sleeve 1230 described for FIGS. 8 and 9, and also for all of theembodiments discussed above and below.

[0082]FIGS. 10 and 11 illustrate another embodiment of a snap-fitassembly 1300, which generally includes a terminal pin 1310, a sleeve1340, and an outer terminal ring 1360. The terminal pin 1310 is adaptedto be coupled with the pulse generator 1105 as shown in FIG. 7C. Thesleeve 1340 is adapted to coupled with the terminal pin 1310 and theouter terminal ring 1360. The terminal pin 1310 extends from a first end1312 to a second end 1314, and includes a coupling portion 1320 integraltherewith. The coupling portion 1320 is formed on an external surface ofthe terminal pin 1310, and in one embodiment, comprises an annularflange 1322. The annular flange 1322, which can partially or completelyencircle the outer surface of the terminal pin 1310, includes matingsurfaces 1324 which are adapted to engage with the sleeve 1340, as willbe described below.

[0083] The sleeve 1340 extends from a first end 1342 to a second end1344, and includes a first set of coupling features 1345. The first setof coupling features 1345 are disposed proximate to the first end 1342of the sleeve 1340. In one embodiment, the first set of couplingfeatures 1345 include a first set of cantilever hooks 1346. The firstset of cantilever hooks 1346 are adapted to deflect from a hinge point1347 and are also adapted to couple with a portion of the outer terminalring 1360. The first set of cantilever hooks 1346 further include, inanother embodiment, mating surfaces 1348. The mating surfaces 1348 aredisposed proximate to tapered portions 1349 of the first set ofcantilever hooks 1346. It should be noted that the first set ofcantilever hooks 1346 refer to a plurality of coupling features, such ascantilever hooks, however, a single cantilever hook can also be used.

[0084] Disposed proximate to the second end 1344 of the sleeve 1340 area second set of coupling features 1356. In one embodiment, the secondset of coupling features 1356 comprise a second set of cantilever hooks1350. The second set of cantilever hooks 1350 are adapted to couple withthe coupling portion 1320 of the terminal pin 1310. The second set ofcantilever hooks 1350, in another embodiment, each include a recess 1352formed therein. The recess 1352 of each of the second set of cantileverhooks 1350 is adapted to receive the annular flange 1322 therein. Itshould be noted that although a second set of cantilever hooks 1350 aredescribed herein, a single cantilever hook can also be used. A taperedingress 1358 is formed on the second set of cantilever hooks 1350 tofacilitate insertion of the terminal pin 1310 therethrough. In yetanother embodiment, the sleeve 1340 also includes a positive stop 1354.The positive stop 1354 has a surface which rests against a portion ofthe outer terminal ring 1360, preventing further movement thereof.

[0085] The outer terminal ring 1360, which couples with the sleeve 1340,extends from a first end 1362 to a second end 1364, and has anintermediate portion 1363 therebetween. The outer terminal ring 1360includes coupling features 1366, which in one embodiment are disposedproximate to the intermediate portion 1363. The coupling features 1366,in another embodiment, include cutouts 1368. The number of cutouts 1368corresponds to the number of hooks in the first set of cantilever hooks1346 of the sleeve 1340. The cutouts 1368 also correspond in shape toreceive the first set of cantilever hooks 1346 therein. In oneembodiment, the cutouts 1368 comprise circular apertures. In anotherembodiment, the coupling features 1366 each include a mating surface1370, which is disposed adjacent the mating surfaces 1348 of the sleeve1340 when the sleeve 1340 is assembled to the outer terminal ring 1360.

[0086] To assemble the snap-fit assembly 1300, the terminal pin 1310 iscoupled with the sleeve 1340, and the sleeve 1340 is coupled with theouter terminal ring 1360. The terminal pin 1310 can be assembled firstinto the sleeve 1340, alternatively, the sleeve can first be coupledwith the outer terminal ring 1360. To assemble the terminal pin 1310 tothe sleeve 1340, the first end 1312 of the terminal pin 1310 is insertedinto the second end 1344 of the sleeve 1340. As the terminal pin 1310 isfurther inserted into the sleeve 1340, the second set of cantileverhooks 1350 are deflected by the annular flange 1322. The terminal pin1310 is further inserted into the sleeve 1340 until the annular flange1322 is seated within the recess 1352. The terminal pin 1310 and thesleeve 1340 assembly is then coupled with the outer terminal ring 1360.

[0087] The first end 1342 of the sleeve 1340 is inserted into the secondend 1364 of the outer terminal ring 1360. As the first end 1342 of thesleeve 1340 is inserted, the first set of cantilever hooks 1346 aredeflected. The sleeve 1340 is further inserted into the outer terminalring 1360 until the tapered portion 1349 of the first set of cantileverhooks 1346 are seated within the cutouts 1368 of the outer terminal ring1360. The mating surfaces 1348 of the cantilever hooks 1346 are placedadjacent to the mating surface 1370 of the outer terminal ring 1360.

[0088] The terminal pin 1310 and the outer terminal ring 1360 are eachformed of a conductive material. The sleeve 1340 is formed from anonconductive material, and acts as an insulator between the terminalpin 1310 and the outer terminal ring 1360, in one embodiment. The sleeve1340 can be formed from various high-performance engineering plastics,unreinforced and reinforced materials including, but not limited topolysulfone, polyimide, polyamide, polyacetal, polyketone,polyetheretherketone, polyester, polycarbonate, polyolefin, or liquidcrystal polymers.

[0089]FIGS. 12 and 13 illustrate another embodiment of a snap-fitassembly 1400 which generally includes a terminal pin 1410, a sleeve1440, and an outer terminal ring 1470. The sleeve 1440 is adapted forcoupling with the outer terminal ring 1470 and the terminal pin 1410.The terminal pin 1410 extends from a first end 1412 to a second end 1414and includes a coupling portion 1420. In one embodiment, the couplingportion 1420 includes tapered projections 1422 which extend away from anexternal surface of the terminal pin 1410. Alternatively, the taperedprojections 1422 can have other shapes such as a rounded projection. Thetapered projections 1422 include at least one mating surface 1424, forcoupling with a portion of the sleeve 1440, as discussed further below.Although a plurality of projections 1422 are discussed, a singleprojection can also be used.

[0090] The sleeve 1440 extends from a first end 1442 to a second end1444, and includes a first set of coupling features 1445 for couplingwith the outer terminal ring 1470. In addition, the sleeve 1440 includesa second set of coupling features 1450 for coupling with the terminalpin 1410.

[0091] The second set of coupling features 1450, in one embodiment,comprise cutouts 1452 formed in cantilever panels 1453. The cantileverpanels 1453 are adapted to deflect when an internal or external force isplaced thereon. The cutouts 1452 correspond in size and shape and areadapted to receive therein the tapered projections 1422 of the terminalpin 1410. In another embodiment, the number of cutouts 1452 correspondto the number of tapered projections 1422. The cutouts 1452 includemating surfaces 1454 which are adjacent to the mating surfaces 1424 ofthe terminal pin 1410 when the sleeve 1440 is assembled with theterminal pin 1410.

[0092] As mentioned above, the sleeve 1440 also includes a first set ofcoupling features 1445 for coupling the sleeve 1440 with the outerterminal ring 1470. The first set of coupling features 1445, which inone embodiment are disposed at the first end 1442 of the sleeve 1440,comprise cantilever hooks 1446 which include tapered portions 1447 andalso mating surfaces 1448. The cantilever hooks 1446 are adapted todeflect when an external or internal force is placed thereon. The firstset of coupling features 1445 are adapted to be received by the outerterminal ring 1470. In another embodiment, a positive stop 1456 isformed integral with the sleeve 1440 and is disposed adjacent to thefirst set of coupling features 1445.

[0093] The outer terminal ring extends from a first end 1474 to a secondend 1476 and includes an inner surface 1472 which receives the sleeve1440 therein. The outer terminal ring 1470 further includes snap-fitcoupling features 1478. In one embodiment, the snap-fit couplingfeatures 1478 comprise a tapered surface 1484 formed proximate to thesecond end 1476 of the outer terminal ring 1470. The tapered surface1484 is formed near a ridge 1480, which engages with the first set ofcoupling features 1445 of the sleeve 1440. In another embodiment, thecoupling features 1478 include a mating surface 1482 which is placedadjacent to the mating surfaces 1448 of the sleeve 1440.

[0094] To form the snap-fit assembly 1400, the terminal pin 1410 isassembled with the sleeve 1440 and the sleeve 1440 is assembled with theouter terminal ring 1470. However, the sleeve 1440 can be assembled withthe outer terminal ring 1470 prior to assembly of the terminal pin 1410with the sleeve 1440. To assemble the terminal pin 1410 with the sleeve1440, the first end 1412 of the terminal pin 1410 is inserted into andthrough the second end 1444 of the sleeve 1440. The first end 1412 isinserted until the tapered projections 1422 are seated within the secondset of coupling features 1450 of the sleeve 1440. As the terminal pin1410 is inserted through the sleeve 1440, the tapered projections 1422deflect the cantilever panels 1453 outward of the sleeve 1440. Thecantilever panels 1453 are deflected until the tapered projections 1422are seated within the cutouts 1452 of the sleeve, and the matingsurfaces 1454 of the cutouts 1452 abut the mating surfaces 1424 of theterminal pin 1410.

[0095] To assemble the sleeve 1440 to the outer terminal ring 1470, thefirst end 1442 of the sleeve 1440 is inserted into the second end 1476of the outer terminal ring 1470. As the sleeve 1440 is inserted into theouter terminal ring 1470, the first set of coupling features 1445 aredeflected as they approach the tapered surface 1484 of the outerterminal ring. The sleeve 1440 is further inserted until the matingsurfaces 1448 are seated against the mating surface 1482 of the outerterminal ring. The cantilever hooks 1446 are retained by the annularridge 1480 of the outer terminal ring 1470.

[0096] The terminal pin 1410 and the outer terminal ring 1470 are eachformed of a conductive material. The sleeve 1440 is formed from anonconductive material, and acts as an insulator between the terminalpin 1410 and the outer terminal ring 1470, in one embodiment. The sleeve1440 can be formed from various high-performance engineering plastics,unreinforced and reinforced materials including, but not limited topolysulfone, polyimide, polyamide, polyacetal, polyketone, polyester,polycarbonate, polyolefin, or liquid crystal polymers.

[0097]FIGS. 14 and 15 illustrate another embodiment of a snap-fitassembly 1500, which includes generally a terminal pin 1510, a sleeve1540, and an outer terminal ring 1570. The terminal pin 1510 extendsfrom a first end 1512 to a second end 1514, and includes at least onecoupling portion 1516. In one embodiment, the coupling portion 1516 isdisposed between the first end 1512 and the second end 1514 of theterminal pin 1510. In another embodiment, the coupling portion 1516comprises an annular projection 1518 which extends from an externalsurface of the terminal pin 1510. The annular projection 1518, inanother embodiment, includes a tapered surface 1522 and also a matingsurface 1520. The coupling portion 1516 allows for the terminal pin 1510to be coupled with the sleeve 1540 using a snap-fit connection.

[0098] The sleeve 1540 is adapted to couple with both the terminal pin1510 and also the outer terminal ring 1570, and extends generally from afirst end 1542 to a second end 1544. Proximate to the first end 1542, isa first coupling feature 1546, which allows for the sleeve 1540 to becoupled with the outer terminal ring 1570. In one embodiment, the firstcoupling feature 1546 comprises an annular projection 1548 including atapered surface 1550 and a mating surface 1552. The sleeve 1540 alsoincludes a second coupling feature 1554 which, in one embodiment,comprises an annular recess 1556. In yet another embodiment, the annularrecess 1556 includes a ridge 1558 and also a mating surface 1560, whichis adapted to couple with the annular projection 1518.

[0099] The outer terminal ring 1570 is adapted to couple with the sleeve1540, and generally extends from a first end 1572 to a second end 1574.The outer terminal ring 1570 is defined in part by an inner surface 1576which is adapted to receive a portion of the sleeve 1540 therein. Theouter terminal ring 1570 further includes at least one snap-fit couplingfeature 1578 which allows for the sleeve 1540 to be coupled with theouter terminal ring 1570. In one embodiment, the coupling feature 1578includes a tapered ingress 1582 which extends to a ridge 1580. The ridge1580 includes a mating surface 1584, and is adapted to retain the firstcoupling feature 1546 of the sleeve 1540. In one embodiment, the taperedingress 1582 and/or the ridge 1580 are formed on the inner surface 1576of the outer terminal ring 1570. In another embodiment, the taperedingress 1582 is formed annularly of the inner surface 1576.

[0100] To assemble the snap-fit assembly 1500, the terminal pin 1510 iscoupled with the sleeve 1540, and the sleeve 1540 is coupled with theouter terminal ring 1570. It should be noted however, that the sleeve1540 can also be first coupled with the outer terminal ring 1570 andthen the terminal pin 1510 is coupled with the sleeve 1540. To couplethe terminal pin 1510 to the sleeve 1540, the first end 1512 of theterminal pin 1510 is inserted into the second end 1544 of the sleeve1540. The terminal pin 1510 is inserted until the coupling portion 1516is seated within the second coupling feature 1554, of the sleeve. Oncethe annular projection 1518 is seated within the annular recess 1556,the mating surface 1520 abuts the mating surface 1560 of the sleeve1540.

[0101] To assemble the sleeve 1540 to the outer terminal ring 1570, thefirst end 1542 of the sleeve 1540 is inserted into the second end 1574of the outer terminal ring 1570. As the sleeve 1540 is inserted into theouter terminal ring 1570, the tapered surface 1550 deflects the taperedingress 1582 of the outer terminal ring 1570. The sleeve 1540 is furtherinserted into the outer terminal ring 1570, until the mating surface1552 of the first coupling feature 1546 abuts the mating surface 1584 ofthe outer terminal ring 1570.

[0102] The terminal pin 1510 and the outer terminal ring 1570 are eachformed of a conductive material. The sleeve 1540 is formed from anonconductive material, and acts as an insulator between the terminalpin 1510 and the outer terminal ring 1570, in one embodiment. Thematerials suitable for the sleeve 1540 are similar to those describedfor the sleeve discussed above in earlier embodiments The snap-fitassembly 1500 provides several advantages in that the assembly allowsfor rotational movement, yet prevents axial movement of the terminal pin1510 relative to the sleeve 1540, and the sleeve 1540 relative to theouter terminal ring 1570. The rotational movement which is allowed bythe snap-fit assembly 1500 is advantageous since the snap-fit assembly1500 can be used in combination with retractable lead designs, or leadswhich otherwise require rotational movement and yet simultaneouslyprevent axial movement.

[0103]FIGS. 16, 17, 18 and 19 illustrate another embodiment of a snapfit assembly 1600, which includes generally a terminal pin 1620 and anouter terminal ring 1660. The terminal pin 1620 and the outer terminalring 1660 are adapted to couple together at a snap-fit coupling, asfurther described below.

[0104] The terminal pin 1620 extends from a first end 1622 to a secondend 1624, and includes a snap-fit coupling portion 1626. In oneembodiment, the coupling portion 1626 is disposed between the first end1622 and the second end 1624. It should be noted that the couplingportion 1626 can be disposed on an external surface or an internalsurface of the terminal pin 1620. In another embodiment, the couplingportion 1626 comprises an annular projection 1640, as shown in FIG. 17.The annular projection 1640 has a semi-circular cross-section, as shownin FIG. 16. In another embodiment, the coupling portion 1626 comprisesat least one projection 1642, which does not extend completely aroundthe outer surface of the terminal pin 1620, as illustrated in FIG. 17. Aplurality of projections 1643 can also be provided, as shown in FIG. 18.In another embodiment, the plurality of projections 1643 are spaced 90degrees apart from one another.

[0105] Disposed through the terminal pin 1620 a bore 1630, where thebore 1630 extends from the first end 1622 to the second end 1624 of theterminal pin 1620. The bore 1630 allows for instruments, such ascatheters, stylets, or guidewires, to be inserted through the terminalpin 1620 and through the lead 1110 (FIG. 7B).

[0106] In yet another embodiment, an insulator is disposed between theterminal pin 1620 and the outer terminal ring 1660. The insulator can bea shim, a tube, a wedge, or a coating placed between the terminal pin1620 and the outer terminal ring 1660. In one embodiment, a dielectriccoating 1628 is disposed on the interfacing surfaces between theterminal pin 1620 and the outer terminal ring 1660. In anotherembodiment, the coating is disposed over the coupling portion 1626. Thedielectric coating 1628 provides insulation for the coupling portion1626 and/or the surface of the terminal pin 1620. Various insulatingmaterials are appropriate for use as the coating 1628 such as: tungstencarbide, aluminum oxide, chromium oxide, zirconium oxide, magnesiumzirconate, acrylic, epoxy, parylene, polyurethane, silicone, teflon, ormolybdenum disulfide. Other materials which are also dielectric,biocompatible, wear resistant, and has a low coefficient of frictionwould also be appropriate. The coupling portion 1626 of the terminal pin1620 is adapted to snap-fit with a coupling portion of the outerterminal ring 1660.

[0107] The outer terminal ring 1660 extends from a first end 1662 to asecond end 1664, and includes a snap-fit coupling portion 1668. Thesnap-fit coupling portion 1668, in one embodiment, is disposed on anintermediate portion 1665 of the outer terminal ring 1660. In anotherembodiment, the coupling portion 1668 is disposed on an inner surface1666 of the outer terminal ring 1660. The coupling portion 1668comprises an annular recess 1670 which is sized and positioned toreceive the snap-fit coupling portion 1626 of the terminal pin 1620therein.

[0108] To assemble the snap-fit assembly 1600, the terminal pin 1620 iscoupled with the outer terminal ring 1660. To assembly the terminal pin1620 to the outer terminal ring 1660, the first end 1622 of the terminalpin 1620 is inserted into the second end 1664 of the outer terminal ring1660. The terminal pin 1620 is inserted until the annular projection1640 is seated within the annular recess 1670 of the outer terminal ring1660. Once the projection 1640 is seated within the recess 1670, furtheraxial movement is prevented. However, rotational movement of theterminal pin 1620 relative to the outer terminal ring 1660 is permitted.

[0109] FIGS. 20-27 illustrate additional embodiments of the lead, leadterminal for the lead system of FIGS. 7A-7C, which includes a terminalassembly 2000 disposed at the proximal end 1112 of the lead body 1110.Referring to FIG. 20, the terminal assembly 2000 includes a terminal pin2010, an insulative sleeve 2030, and an outer terminal ring 2060, whichare all coupled together such that, after assembly, axial movement ofthe components is prevented. Optionally, the terminal assembly 2000 alsoincludes inner tubing 2200, such as silicone tubing, where the innertubing 2200 is disposed between the terminal pin 2010 and the insulativesleeve 2030.

[0110] The terminal pin 2010, as shown in FIG. 21, extends from a firstend 2012 to a second end 2014, where the second end 2014 of the terminalpin 2010 is adapted for coupling with the pulse generator 1105 (FIG.7A), as discussed above. The first end 2012 of the terminal pin 2010 isadapted to be inserted into the insulative sleeve 2030, as will befurther described below.

[0111] The terminal pin 2010 includes an assembly portion 2016 which isdisposed near the first end 2012. The assembly portion 2016 includes anouter surface 2018 which is adapted to be received within the sleeve2030. The outer surface 2018 includes a portion 2019 which extendsannularly outward from the outer surface 2018. The portion 2019 isengagable by the sleeve 2030, as discussed below, and prevents axialmovement of the terminal pin 2010 relative to the sleeve 2030. Inaddition, the outer surface 2018 includes a stop 2020 extendingtherefrom. The stop 2020 assists in the assembly process of the sleeve2030 on the terminal pin 2010.

[0112] In one embodiment, the terminal pin 2010 further includesanti-rotation features 2022, as shown in FIG. 22. One example of theanti-rotation features 2022 include axial grooves 2024 disposed withinthe outer surface 2018 of the terminal pin 2010 near the first end 2012of the terminal pin 2010. In another example, as shown in FIG. 23, theanti-rotation features 2022 include at least one flat 2026 disposed onthe outer surface 2018 of the terminal pin 2010. The anti-rotationfeatures 2022 prevent the rotation of the terminal pin 2010 relative tothe sleeve 2030. Since the terminal pin 2010 is prevented from rotatingrelative to the sleeve 2030, seal breakdown between the terminal pin2010 and the sleeve 2030 is minimized and/or eliminated.

[0113] The assembly 2000 also includes a sleeve 2030, as shown ingreater detail in FIG. 24, comprising a generally cylindrical structure.The sleeve 2030 is an insulator between the terminal pin 2010 and theouter terminal ring 2060, where the sleeve 2030 electrically insulatesthe terminal pin 2010 from the outer terminal ring 2060. In addition,the sleeve 2030 provides a mechanical connection between the terminalpin 2010 and the outer terminal ring 2060. The sleeve 2030 is formed ofnonconductive material, such as various high-performance plasticsincluding, but not limited to, polysulfone, polyimide, polyamide,polyacetal, polyketone, polyester, polycarbonate, polyolefin, orpolyetheretherketone (PEEK). In one embodiment, the sleeve is formed ofPEEK 150G or 450G. The PEEK, in combination with the structure of thesleeve 2030, allows for the sleeve 2030 to be molded, extruded, ormachined for tighter tolerances or for providing precision structures.

[0114] The sleeve 2030 extends from a first end 2032 to a second end2034. Disposed through the sleeve 2030 is a bore 2036, where the bore2030 is adapted to receive the terminal pin 2010 therein, where theterminal pin 2010 also includes a bore therethrough. The bore of theterminal pin 2010 allows for instruments, such as catheters, stylets, orguidewires, to be inserted through the proximal end of the lead 1110(FIG. 7B).

[0115] The insulative sleeve 2030 is defined in part by an externalsurface 2038 which has at least one coupling feature 2040 thereon. Theat least one coupling feature 2040 allows for the insulative sleeve 2030to be coupled with the outer terminal ring 2060 with a snap-fitconnection. For instance, the at least one coupling feature 2040comprises a ring latch 2042 which couples the insulative sleeve 2030with the outer terminal ring 2060. The ring latch 2042 comprises atapered annular shoulder 2044 extending from the external surface 2038.Optionally, the insulative sleeve 2030 includes a relief groove 2046(FIG. 25) disposed adjacent to the ring latch 2042, which allows thering latch 2042 to more easily deflect as it is installed within theouter terminal ring 2060.

[0116] Alternatively, the at least one coupling feature 2040 furtherincludes, a pin latch 2048 which extends outward from the externalsurface 2038 of the insulative sleeve 2030. The pin latch can beprovided in addition to or in alternative to the ring latch 2042. Thepin latch 2048 secures the insulative sleeve 2030 to the terminal pin2010. The pin latch 2048 comprises a tapered portion 2050 which isadapted to fold over a hinge point 2052. The hinge point 2052 comprises,in one embodiment, a relief groove 2054 which allows the pin latch 2048to fold thereover. Optionally, a second relief groove 2056 is providedat an opposite end 2058 of the pin latch 2048 hinge point 2052, whichpermits the pin latch 2048 to deflect toward the external surface 2038of the insulative sleeve 2030. As the pin latch 2048 is deflected towardthe external surface 2038, an interior surface 2039 of the insulativesleeve 2030 is deflected inward and in to the terminal pin 2010, asfurther described below. The lead can be altered from being rotatable tobeing non-rotatable, for instance by modifying the size of the pin latch2048 and/or modifying the relative position of the pin latch 2048.

[0117] In another embodiment, as illustrated in FIG. 24, the insulativesleeve 2030 further includes a bump stop 2059. The bump stop 2059comprises a semi-circular projection which extends annularly from theexternal surface 2038 of the insulative sleeve 2030. The bump stop 2059assists in the assembly of the outer terminal ring 2060 on to theinsulative sleeve 2030 in that the terminal ring 2060 is advanced untilit reaches the bump stop 2059. The bump stop 2059 further assists inpreventing the axial movement of the outer terminal ring 2060 past thebump stop 2059 of the insulative sleeve 2030.

[0118] The interior surface 2039 of the insulative sleeve 2030 istapered from the first end 2032 to the second end 2034 such that theinner diameter at the first end 2032 is larger than the inner diameterat the second end 2034. The tapered features of the insulative sleeve2030 allow for the sleeve 2030 to better compress against tubing 2200 onthe terminal pin, and to provide a seal therebetween.

[0119] Referring to FIGS. 26A and 26 B, the outer terminal ring 2060 isshown in greater detail. The outer terminal ring 2060 has a generallycylindrical structure, and extends from a first end 2062 to a second end2064. The outer terminal ring 2060 includes a coupling portion 2066formed on an internal surface 2068 of the outer terminal ring 2060. Thecoupling portion 2066 of the outer terminal ring 2060 couples with thesleeve 2030 to form a snap-fit connection and prevents the outerterminal ring 2060 from moving axially relative to the insulative sleeve2030. The coupling portion 2066 includes an annular recess 2069 which issized and positioned to receive the ring latch 2042 of the sleeve 2030therein. The outer terminal ring 2060 optionally includes anti-rotationfeatures 2070. The anti-rotation features 2070 comprises V-shapedgrooves 2072 on the internal surface 2068, as shown in FIG. 27.

[0120] To assemble the assembly 2000, the first end 2012 of the terminalpin 2010 is inserted into the first end 2032 of the sleeve 2030 untilcontact is made with pin stop 2020. Optionally, tubing 2200, such assilicone tubing, is disposed over the terminal pin 2010 prior to itsinsertion into the sleeve 2030. The outer terminal ring 2060 is advancedover the terminal pin 2010 and sleeve 2030 until the ring latch 2042mates with the recess 2069 of the outer terminal ring 2060. As the outerterminal ring 2060 is advanced over the terminal pin 2010, the pin latch2048 folds over the hinge point 2052. As the pin latch 2048 folds overthe hinge point 2052, the sleeve 2030 is forced toward the terminal pin2010 and captures pin flange 2023, preventing axial movement of pin 2010relative to sleeve 2030.

[0121] Several embodiments are described above which relate to snap fitfeatures for the terminal pin and the outer terminal ring and,optionally, the sleeve. It should be noted that the features shown inthe drawings can be exchanged between embodiments shown in the variousdrawings. In addition, the coupling features have been described on anexternal surface of one component which mates with an internal surfaceof another component. However, the coupling features can be moved frominternal to external surfaces and vice versa to accommodate the snap-fitfeatures and/or the press-fit features. Furthermore, the lead design isnot limited to the particular embodiments shown or described above, andcan be applied to various medical devices. It should be further notedthat embodiments discussed for the distal end of the lead can becombined with any of the rotatable embodiments for the proximal end ofthe lead. The lead can be altered from being rotatable to beingnon-rotatable.

[0122] The lead assembly described above provides several advantages,for example, the ease of manufacturability is increased in thatthrough-put times are reduced. The individual components can be snappedtogether, as opposed to waiting for messy bonding or long cure times.Bonding blocks, used for the bonding process, would be eliminated, whichare expensive and difficult and costly to clean. A consistent andincreased strength of coupling would be achieved using the snap fitdesign since bonding is variable based on the operator. Yet anotheradvantage is that the geometry of the snap fit connector provides aninsulation with a known thickness, which allows for a repeatabledielectric strength. Furthermore, the active fixation element of thelead does not require the use of a stylet, since the terminal pin isused to extend and retract the active fixation element. In addition, themovement assembly allows for the lead to withstand high shearing forcesapplied between the terminal pin and the outer terminal components suchas the ring.

[0123] The external features of the insulative sleeve allow the sleeveto be manufactured in an inexpensive manner, and yet provide thestructure which prevents axial movement of the components. In addition,the features allow for the components to be assembled withoutsubstantial orientation requirements, which assists in ease of assemblyand decreases labor costs.

[0124] It is to be understood that the above description is intended tobe illustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reviewing the abovedescription. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A lead comprising: a lead body extending from adistal end to a proximal end; at least one conductor disposed within thelead body and extending from the distal end to the proximal end of thelead body; an outer terminal ring coupled with the lead body; a terminalpin disposed at the proximal end of the lead body; and an insulativesleeve disposed between the outer terminal ring and the terminal pin,where the insulative sleeve is coupled with the outer terminal ring witha snap-fit connection; and a pin latch disposed on an outer peripherysurface of the insulative sleeve, the pin latch rotatable about a hingepoint.
 2. The lead as recited in claim 1, wherein the sleeve and/or thering include at least one anti-rotation feature.
 3. The lead as recitedin claim 2, wherein the anti-rotation features comprise axial groovesdisposed on an inner surface of the outer terminal ring.
 4. The lead asrecited in claim 2, wherein the axial grooves comprise V-shaped grooves.5. The lead as recited in claim 2, wherein the anti-rotation featurescomprise a flat formed on the terminal pin.
 6. The lead as recited inclaim 2, wherein the anti-rotation features comprise axial groovesdisposed on an outer surface of the terminal pin.
 7. A lead comprising:a lead body extending from a distal end to a proximal end; at least oneconductor disposed within the lead body and extending from the distalend to the proximal end of the lead body; an outer terminal ring coupledwith the lead body; a terminal pin disposed at the proximal end of thelead body; and an insulative sleeve disposed between the outer terminalring and the terminal pin; and a pin latch disposed on an outerperiphery surface of the insulative sleeve, the pin latch rotatableabout a hinge point to deflect and couple the insulative sleeve with theterminal pin.
 8. The lead as recited in claim 7, further comprisinginner tubing disposed between the sleeve and the terminal pin.
 9. Thelead as recited in claim 7, wherein an inner surface of the sleeve istapered from a first end to a second end.
 10. The lead as recited inclaim 7, wherein the insulative sleeve is formed ofpolyetheretherketone.
 11. The lead as recited in claim 7, wherein thesleeve is longer than the terminal pin.
 12. The lead as recited in claim7, further comprising a means for preventing the insulative sleeve fromrotating relative to the terminal pin and/or the outer terminal ring.13. The lead as recited in claim 8, wherein the insulative sleeve iscoupled with the outer terminal ring with a snap-fit coupling.
 14. Alead comprising: a lead body extending from a distal end to a proximalend; at least one conductor disposed within the lead body and extendingfrom the distal end to the proximal end of the lead body; an outerterminal ring coupled with the lead body; a terminal pin disposed at theproximal end of the lead body; and an insulative sleeve disposed betweenthe outer terminal ring and the terminal pin; anti-rotation featuresformed in one or more of the outer terminal ring, the terminal pin, orthe insulative sleeve; and inner flexible tubing disposed between theinsulative sleeve and the terminal pin.
 15. The lead as recited in claim14, wherein the anti-rotation features comprise axial grooves disposedon an inner surface of the outer terminal ring.
 16. The lead as recitedin claim 15, wherein the axial grooves comprise V-shaped grooves. 17.The lead as recited in claim 14, wherein the anti-rotation featurescomprise a flat formed on the terminal pin.
 18. The lead as recited inclaim 14, wherein the anti-rotation features comprise axial groovesdisposed on an outer surface of the terminal pin.
 19. The lead asrecited in claim 14, wherein sleeve further includes a pin flange, and apin latch captures the pin flange.
 20. A method comprising: disposing aterminal pin within a bore of an insulative sleeve, the insulativesleeve including a ring latch and a pin latch, and the pin latchincluding a hinge point; disposing the terminal pin and sleeve within anouter terminal ring, the outer terminal ring having an inner surfacehaving a recess therein; and advancing the insulative sleeve into theouter terminal ring, including mating the ring latch within the recessand hinging the pin latch over the hinge point.
 21. The method asrecited in claim 20, further comprising disposing tubing over theterminal pin prior to disposing the terminal pin within the bore of theinsulative sleeve.
 22. The method as recited in claim 20, whereinhinging the pin latch over the hinge point includes deflecting the pinlatch over the hinge point.
 23. The method as recited in claim 20,wherein hinging the pin latch over the hinge point includes hinging thepin latch over a relief groove.
 24. A lead comprising: a lead bodyextending from a distal end to a proximal end; at least one conductordisposed within the lead body and extending from the distal end to theproximal end of the lead body; an outer terminal ring coupled with thelead body; a terminal pin disposed at the proximal end of the lead body;an insulative sleeve disposed between the outer terminal ring and theterminal pin; and inner compressible tubing compressed between theterminal pin and the insulative sleeve.
 25. The lead as recited in claim24, wherein the insulative sleeve includes at least one pin latch, andthe at least one pin latch is rotated about a hinge point and deflectedtoward the insulated sleeve to engage a portion of the insulativesleeve.
 26. The lead as recited in claim 25, further comprising a firstrelief groove at a hinge point of the pin latch, and the pin latch isfolded over the first relief groove.
 27. The lead as recited in claim26, further comprising a second relief groove at an opposite end of thepin latch than the first relief groove.
 28. The lead as recited in claim24, wherein an interior surface of the insulative sleeve is tapered. 29.The lead as recited in claim 24, wherein the outer terminal ringincludes an annular recess, where the annular recess engages a ringlatch of the sleeve.
 30. The lead as recited in claim 24, wherein thesleeve includes a tapered ring latch disposed within a recess of theouter terminal ring.
 31. The lead as recited in claim 30, wherein thesleeve has a relief groove disposed adjacent to the ring latch.
 32. Thelead as recited in claim 24, wherein an interior surface of theinsulated sleeve is deflected into the terminal pin as the pin latch isdeflected toward an exterior surface of the insulative sleeve.